Aging and drying of gels

George W. Scherer

Research output: Contribution to journalArticlepeer-review

147 Scopus citations

Abstract

This review describes the chemical and physical processes occurring during the aging and drying of an inorganic gel. The chemical reactions that lead to gelation are shown to continue long after the solution gels, causing changes in the composition, structure, and properties of the gel. The formation of new crosslinks produces shrinkage (syneresis) and increases the modulus and viscosity of the gel, so that aging reduces the subsequent shrinkage during drying. If the solubility of the solid phase is drying, the small pores of the gel develop high capillary pressures that results in shrinkage. If the exterior surface shrinks much faster than the interior, the differential strain can cause warping and cracking; very slow drying is generally required to prevent such catastrophes. Fracture is most likely at the moment that shrinkage stops and the liquid/vapor meniscus moves into the gel; after that point, the meniscus may remain smooth or may become unstable and ragged. The theory of drying is reviewed and shown to account for the observed behavior. Several strategies are described that minimize the tendency of the gel to crack.

Original languageEnglish (US)
Pages (from-to)77-92
Number of pages16
JournalJournal of Non-Crystalline Solids
Volume100
Issue number1-3
DOIs
StatePublished - Jan 1 1988
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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